Well, I got Box2D integrated. Which was amusing, as it shares some typedefs with ProtonSDK. It's kind of amusing that the B2D guys went to the trouble of naming everything b2 and then put a base header with some highly generic defs like int32 in there.
It's not quite working at the minute, the renderer's getting a weird-ass fixture list. I think I'm missing something. Will be at it today. Once it's working, axons should start dropping into nodes.